Effects of Radiation Heating on Modal Characteristics of Panel Structures

Hypersonic flight vehicles will be subjected to extremely high surface temperatures and large temperature gradients. Both the temperature-dependent material properties and the thermal stresses resulting from the temperature distributions will influence the modal characteristics of the structure. Ahigh-temperature modal survey was performed on a flat plate and a stiffened plate to investigate the effects of a nonuniform temperature field on the modal characteristics during the test. A finite element simulation of these high-temperature modal tests was carried out and the contributions from temperature-dependent material properties and thermal stresses were investigated. Both the testing and analytical results show that the thermal stresses have a much greater effect on the modal characteristics than the change of the material properties due to heating. Therefore, much care needs to be taken to determine the temperature distribution during high-temperature modal tests.